The overall goal of this project is to determine whether the macronutrient composition of a weight reduction diet causes a difference in the amount of weight change or in the subject's perceived satiety to the diet. In order to address this question, we will randomly assign forty-five subjects to one of the following: 1) a high carbohydrate, moderate protein, low-fat diet, 2) a high carbohydrate of low glycemic index, moderate protein, low fat, or 3) a high fat, moderate carbohydrate, moderate protein diet. Evaluation of the effectiveness of each treatment approach will be evaluated primarily by changes in body weight of subjects and secondarily by evaluation of health and nutrition related parameters and the satiety value of each paradigm. To perform these experiments, we will recruit healthy, overweight (BMI 30-40) men and women ages 18 - 70 from the University and Twin Cities Metropolitan community. Participants will be asked to come to the Clinical Research Center in the fasting state and have their blood drawn for the determination of nutritional and medical measures. During the feeding phase of the study, subjects will be required to come to the GCRC for one meal a day. All meals will be prepared in the Metabolic Kitchen at the GCRC. All subjects will be required to come to the GCRC for endpoint determination weekly. After completion of the feeding phase of the study, subject will be instructed in the diets for home implementation. Follow-up visits will be scheduled for 12 and 24 weeks post active treatment to assess long term compliance and metabolic parameters.